1. Field of the Invention
The present invention relates to a connective structure for coupling two printed circuit boards facing one another.
2. Prior Art
In order to connect two mating printed circuit boards 1 and 2 together, a female connector 3 mounted on one of the circuit boards (hereinafter referred to often as xe2x80x98firstxe2x80x99circuit board) 1 has been fitted on a male connector 4 mounted on the other circuit board (viz., xe2x80x98secondxe2x80x99 circuit board) 2 in a xe2x80x98lug-into-recessxe2x80x99 manner shown in FIG. 13(a). In such a case, one of the first and second circuit boards 1 or 2 has to be inclined for visually checking the correct positions of male and female connectors 3 and 4 snapping into place. This operation has often or sometimes caused a certain xe2x80x98prizingxe2x80x99or distortion in the one connector 3 relative to the other 4, thereby resulting in their defective fitting engagement.
In spite of this problem, it has recently been required to minimize the stacking distance between those printed circuit boards 1 and 2 stacked one on another. Accordingly, the male and female connectors 3 and 4 for coupling them have been made much lower in height. Such shorter connectors have rendered difficult the visual check of their relative position, even if one circuit board 1 would be inclined as shown In FIG. 13(b). An effective connection length (perpendicular to the boards) of those connectors has thus been reduced to impair reliability of their electric connection.
A proposal that was made to resolve the problem of such a shortened connection length resulting from the thinner connectors and to provide an improved connector is disclosed in the Japan Patent Laying-Open Gazette No. 8-250240. According to this proposal, an opening formed in one printed circuit board is wide enough to receive a male connector (viz., header), wherein its surface not facing the other circuit board is used to mount thereon electronic devices and the like. Such a connective structure improved to more surely couple two printed circuit boards facing one another has however failed to resolve the xe2x80x98prizingxe2x80x99 distortion of connectors. The mating male and female connectors may accidentally take incorrect positions relative to each other, causing mutual collision of their housings. In such an event, a strong stress will be imparted to the soldered portions of male connector (viz., header) that has a surface to mount the electronic devices and the like. Consequently, serious cracks are likely to be produced in the soldered portions to thereby fail to establish a reliable electric connection.
The present invention was made in view of the drawbacks inherent in the prior art structure. An object is to provide, for coupling two printed circuit boards facing one another, a connective structure improved such that its portions are surely protected from distortedly fitting one in another in spite of a reduced distance between the circuit boards, so as to establish a reliable electric connection.
In order to achieve this object, the invention provides a connective structure for coupling a first and second printed circuit boards facing one another, wherein the structure comprises a female connector surface-mounted on the first printed board and a male connector mounted on the second board so as to fit on the female connector. The male connector has a housing and a plurality of positioning pins extending from opposite lateral ends of the housing towards the first printed circuit board. Free ends of the positioning pins protrude beyond a top of the housing, and positioning openings are formed in the first circuit board so that the pins are inserted in the positioning openings in order to couple the male and female connectors at their positions correct and accurate relative to each other.
Preferably, the female connector may be of a thinned type secured in an opening formed in the first circuit board so as to be disposed on its free surface not facing the second board.
Also preferably, the positioning pins penetrating the positioning openings may be of a height to jut from the free surface such that correct mutual fitting of the male and female connectors can be detected visually.
There may be a case wherein female connector on the first circuit board has the housing whose end regions overlie the positioning openings. In this case, guide holes coincident with the positioning slots may be formed in those end regions. Ends of the positioning pins inserted through the positioning openings will thus be exposed in the guide holes, for visual check of said pins.
Preferably, a basal end of each positioning pin may protrude down from a bottom of the female connector housing so as to serve as a further positioning pin for precisely dispose the male connector relative to the second circuit board.
In any case, the positioning pins may be formed simultaneously and integrally with the male connector housing, or alternatively be made of a metal as discrete pieces to be subsequently insert-molded with or pressed into the housing.